Hi team, Fixing a bug in the Mapnik GDAL code ( https://github.com/mapnik/mapnik/tree/master/plugins/input/gdal) where the return value of RasterIO() isn't checked (so eg. if a component TIFF in a VRT is unavailable it just trucks right along rendering blank images without error) and it appears to me like the usage of GDAL could be optimised a bit in https://github.com/mapnik/mapnik/blob/master/plugins/input/gdal/gdal_featureset.cpp
I'm curious whether any of the following will actually make much difference, or whether GDALs caching nullifies most of it already? Or whether there are potentially other obvious performance optimisations? * Favouring dataset.RasterIO() over band.RasterIO() to prevent up to 4x raster reads * Use of GetBlockSize() to read on block boundaries, then cropping data later. * Use GetMaskBand()/GetMaskFlags() to simplify nodata/alpha handling (probably won't impact performance but might get rid of a bunch of code) Cheers, Rob :) -- *Koordinates*PO Box 1604, Shortland St, Auckland 1140, New Zealand Phone +64-9-966 0433 koordinates.com <https://koordinates.com/about>
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